Electrons , protons inside an atom are called anti-particles if they have opposite charge. The name of the substance made with such anti-particles is antimatter. Normally the charge of electrons is negative but the charge of protons is positive but in antimatter their charge will be positive and negative respectively. That is the complete opposite. The following is a picture of an antihydrogen atom. If the antihydrogen atom comes in contact with a normal hydrogen atom, both will be destroyed. Did n't you hear the name of the antidote in Jafar Iqbal Sir's book Octopus Eyes ? This antimatter is called antimatter in Bengali. When ordinary matter and antimatter come close to each other, there will be a massive explosion and energy will be generated.